The invention relates to a valve, especially a solenoid valve with a controllably movable valve body, said body cooperating with inlet or outlet openings for a flowing medium, said openings being provided in a housing or the like.
Many solenoid valves are known (German Offenlegungsschrift No. 18 06 040), wherein conical valve bodies cooperate with corresponding valve seats. There is limited flexibility in such designs because the masses become too great at large nominal widths. In particular, valves which open when a magnet is energized also suffer from problems relating to the magnetic forces to be transmitted and to the required stroke. For this reason, so-called plate valves have been used for solenoid valves (German Offenlegungsschrift No. 26 50 393), wherein flat, membrane-like valve bodies cooperate with corresponding seats. However, manufacture of such valves is not simple. The same remarks that were made regarding the valve designs mentioned hereinabove also apply to the transmission of magnetic forces and the length of the stroke.
An object of the invention is to design a valve in such a manner that the actuating force can be kept as small as possible even when controlling large nominal widths, so that small magnet units which can be manufactured at negligible expense can be used as actuating elements when electromagnets are used.
The invention contemplates an arrangement wherein the valve body is designed as a sealing body unrollable (sealing body can be unrolled from its rest position) on a surface containing the inlet and outlet openings. The fact that, according to the invention, the sealing body need not be lifted off the valve seat, but is merely unrolled over the latter, means that extremely small actuating forces will suffice to ensure the opening or closing of the inlet or outlet openings.
In advantageous preferred embodiments of the invention, the sealing body comprises a strip of sealing material, and the strip is made in the form of an annular loop of elastic material, said loop being unrollable on a sealing plane containing the inlet or outlet openings. This design makes it possible to avoid using roller bodies or the like, so that the total mass to be moved can be kept as small as possible. Valves of this type are therefore especially suitable for electromagnetic actuation, assuming no large magnetic forces and therefore no large magnet parts.
The annular loop can advantageously be guided between the sealing plane and a matching plane, the distance between which is smaller than the diameter of the annular loop. Consequently, the annular loop is pressed into an oval shape, so that it always rests against the sealing surface with a certain pressure and can also apply the restoring force simultaneously when the sealing surface and the matching surface are inclined at an angle to one another. The annular loop located between the two surfaces is always pressed in the direction in which the end loop with the greater radius is located, and it is possible to connect this annular loop with a body on which the actuating force acts, said force then having to act only in one direction, namely, opposite to the restoring force of the annular loop itself.
It has also been found especially advantageous according to other preferred embodiments of the invention to install two annular loops between the sealing and matching surfaces, said loops being fastened together at one point on their circumferences, because this design produces a much more sensitively operating valve body element, which also permits a simple arrangement of the actuating element, namely, when a plate which serves as a stop on the housing is located between the circumferential areas which are fastened together, said plate being provided with a part made of magnetic material. The stop then serves, on the one hand, to delimit the return movement of the two annular loops and on the other hand, as an actuating element when magnetic forces are applied.
There are two basic ways in which the magnetic drive can be provided in accordance with preferred embodiments of the invention. If the magnetic lines of force flow at right angles to the direction of movement of the two annular loops, the magnetic part can advantageously consist of two tabs projecting into the space enclosed by one annular loop, said tabs being located approximately in the direction of movement and at right angles to the above-mentioned plate mounted between the annular loops. When the tabs are either themselves placed at a small angle to the plane which is located at right angles to the plate and in the direction of movement, or are provided with a correspondingly bent area, when a magnetic field is applied and the magnetic matching surfaces of a magnetic yoke are appropriately arranged, very simple and effective actuation becomes possible. In arrangements where the magnetic lines of force run in the direction of movement, a simple design is produced by the magnetic part being a rod located in the area surrounded by one annular loop. This embodiment also has the advantage that two or more double loops can be located in the same magnetic field, said field being produced externally. In this embodiment, for example, two double loops can be provided, said loops being held parallel to one another in a guide part, said part being surrounded by a common magnet part. One double loop can have the magnetic rod located in the vicinity of one end loop and the other at the opposite end loop. If each double annular loop is then subjected to a restoring force which acts in a direction opposite to the other, which is possible either as a result of an appropriate angular positioning of the sealing and matching surfaces, as mentioned above, or by the arrangement of restoring springs, this design can produce an embodiment of a valve which has all of the connections on one side, but some of the openings are closed when the magnet is energized and the others are open. This embodiment therefore permits the design of multi-path valves, especially if the openings in the housing to be closed are connected appropriately with one another or if more than two double-loop pairs are provided.
The invention also provides the possibility of manufacturing a valve with only one annular loop, which simultaneously closes some of the openings while opening others, if an opening is provided in the vicinity of one end loop and another in the area of the other end loop. Finally, it is also contemplated to provide the sealing surfaces with a plurality of inlet or outlet openings located at right angles to the direction of movement, whereby, on the one hand, the throughput or the nominal width can be increased without increasing the stroke and, on the other hand, there is still the possibility of providing a row of openings in the vicinity of one end loop, and a portion, preferably half of these openings, being designed to supply the medium to be controlled and the other part serving to remove the medium from the housing, so that flow paths with a large nominal width can be opened or closed when the annular loop is unrolled. When the covered and/or exposed opening parts are divided into inlet and outlet halves, the valve system operates in a directionally neutral manner with respect to influx and pressure. This design can also be implemented by disposing a number of openings at each of the two end loops according to yet further preferred embodiments of the present invention.